Integrated circuits (ICs) formed on semiconductor substrates include multiple active and passive components. Although it is desirable to verify that each component in the ICs complies with its specific design specification, typically, after integrated into a circuit, the components can no longer be readily tested. Therefore, “stand-alone” copies of the individual IC components, which are the components fabricated with the same process and with the same physical/electrical characteristics as the IC components, are fabricated on the wafer. It is assumed that the physical/electrical properties measured for the “stand-alone” copies represent those of the non-tested IC components in the ICs.
During testing, a “stand-alone” copy, which is commonly referred to as “device-under-test” (DUT), is electrically connected to test pads and pad leads, which are further connected to an external test equipment. Although the measured physical/electrical properties should accurately represent those of the DUT, the test pads and pad leads have their own physical/electrical characteristics that contribute to the measured characteristics of the DUT. The contributions from the test pads and test leads are known as “parasitics”, which include, for example, parasitic resistance, parasitic capacitance, and parasitic inductance, etc. The parasitics are factored out or extracted by a process known as “de-embedding” to obtain the intrinsic characteristics of the DUT.
In the simulations of the IC devices, however, some of the parasitics are difficult to be factored out. For example, in the simulation of transmission lines, the simulated ports for receiving input signals and extracting output signals are set on transmission lines. Setting ports on transmission lines also introduces parasitics. There were no effective methods for removing the parasitics from the simulated characteristics of the transmission lines. On the other hand, with the sizes of the integrated circuit devices became increasingly smaller, and the operation frequency of the integrated circuit devices became increasingly higher, the parasitics became increasingly more severe.